ESM stands for [ECMAScript modules](https://nodejs.org/api/esm.html#modules-ecmascript-modules), which is a modern module system introduced in ES2015 that allows JavaScript code to be organized into reusable, self-contained modules. ESM is now the standard for both [browser](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules) and [Node.js](https://nodejs.org/api/esm.html) environments, replacing older module systems like [CommonJS (CJS)](https://nodejs.org/api/modules.html) and [AMD](https://requirejs.org/docs/whyamd.html).
